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Old 03-01-2012, 09:11 PM   #88 (permalink)
mort
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Quote:
Originally Posted by Old Mechanic View Post
Another reason I think this is true is when you check the compression of any engine, you have to open the throttle to get a better reading. When you do this the cranking speed slows down slightly, which also indicates it takes more work to push the air through the engine with the throttle wide open.
regards
Mech
Hi Mech,
Is open throttle pumping through the exhaust valve (etc.) a bigger load than closed throttle pumping through the throttle (etc.)? A real time measurement of cylinder pressure during a cranking compression test might tell - maybe somebody could check it out?

-mort
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